Electric switch



Feb. 26,1963 5. F. BEACH ETAL 3,079,474

ELECTRIC swrrcu Filed March 24, 1961 s Sheets-Sheet 1 Fig.3.

INVENTORS Euirl E Beach and Chester W. Up'ton Jr.

BY w/zo-ww ATTORNEY Feb. 26, 1963 E. F. BEACH ETAL ELECTRI SWITCH 3 Sheets-Sheet 2 Filed March 24, 1961 Feb. 26, 1963 '3 Sheets-Sheet 3 Filed March 24, 1961 Tulip 7 m m o m n a H 2, m U 5 W? 8 6% J M \lh/ 4/ z z Fig .9.

United States Patent 3,079,474 ELECTRHZ SWlTCH Earl F. Beach, Penn Township, Allegheny County, and Chester W. Upton, J12, Penn Township, Westrnoreland County, Pa., assignors to Westinghouse Eieetric Imporation, East Pittsburgh, Pa., a corporation of Pennsyl- Vania Filed Mar. 24, 1961, Ser. No. 98,240 8 Claims. (Ci. Zita-48) This invention relates, generally, to electric switches and, more particularly, to disconnect switches having pivotal blades.

Generally, the pivotal blade type of disconnect switch includes a blade having one end pivotally attached to a fixed support mounted on a stationary insulating stack and having the other end adapted for swinging motion about the pivot to a point between the spaced jaws of fixed contacts mounted upon another insulating stack whereupon rotation of the blade about its longitudinal axis provides high pressure engagement with the fixed contact jaws. When the switch is to be opened, the blade is first axially rotated to efiect disconnection between the jaws and the blade, and thereafter the blade is swung to the fully open condition. To efiect closing of the disconnect switch, the blade is swung between the jaws and thereafter axially rotated to effect high pressure contact between the blade and the fixed contacts. The swinging and rotational motions of the blade are effected by means of a toggle linkage comprising an operating crank mechanism connected to operate a blade rotating linkage wherein a single continuous movement of the crank in a first direction will cause the blade rotating mechanism to first rotate the blade about its longitudinal axis to efiect disconnection between the jaws and the blade and, thereafter, swing the blade about its pivot point, and, wherein a reverse movement of the operating crank will reverse the blade swinging and rotating procedure. Usually, an extensible member of one type or another is included in the toggle mechanism for automatically extending the length of one of the toggle members, within prescribed limits, to maintain the rotary and swinging movements of the blade substantially sequentially separated so that contact between the swinging blade and the jaws may be completely broken by axial movement of the blade before the blade begins its swinging motion, thus reducing the operating efiort required to operate the blade. Usually, such toggle linkages include relatively complicated structure required to hold the blade in contact with the fixed jaws in opposition to a blade opening force resulting from high momentary overcurrent conditions. Reference is made to Patent No. 2,531,165, filed by E. Scheuerrneyer and patented November 21, 1950, showing a compressible spring biasing the extensible link to hold the blade closed and to Patent No. 2,673,902, filed by G. E. Heberlein patented March 30, 1954, showing a threaded extensible member.

It is an object of this invention to provide in a pivotal blade disconnecting switch a simplified, durable operating mechanism for providing axial rotation and swinging movement of the blade substantially in sequence and at the same time provide for preventing the tendency of the blade to move with respect to the fixed contacts in response to high momentary overcurrent conditions.

It is another object of this invention to provide simplified blade counter-balancing means which are essentially interchangeable to provide counter-balancing when the disconnect switch is mounted either horizontally, vertically, or in an inverted manner.

Other objects of this invention will be explained fully hereinafter or will be apparent to those skilled in the art.

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In accordance with the present invention, there is provided a simplified blade operating mechanism for permitting pivotal motion of the blade substantially separate from rotational motion of the blade, in combination with fixed contact jaws of a type adapted for magnetically holding the blade closed in response to momentary high currents to thus render unnecessary a more complicated operating mechanism which would be required to hold the switch closed under such high fault current condition to prevent contact burning.

For a better understanding of the nature and objects of the invention, reference may be had to the following detailed description, taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a view, in side elevation, of a disconnect switch structure assembly showing the principal features of this invention;

FIG. 2 is a view, in top plan, of the disconnect switch of FIG. 1;

FIG. 3 is a view, in end elevation, of the reverse loop type contact jaws of the disconnect switch of FIGS. 1 and 2;

FIG. 4 is an enlarged fragmentary elevational view, taken partly in section, of the disconnect switch of FIGS. 1 and 2;

FIG. 5 is an enlarged fragmentary top plan view, taken partly in section, of the disconnect switch of FIGS. 1 and 2;

FIG. 6 is an enlarged view, in side elevation, of the bridging member electrically connecting the disconnect blade to the terminal straps;

FIG. 7 is a partial plan view of the bridging member of FIG. 6;

FIG. 8 is an enlarged fragmentary side elevational view, taken partly in section, of a disconnect switch of the type shown in FIGS. 1 and 2, but showing a modification in the counter-balancing mechanism employed for utilization of the disconnect switch in a vertically mounted position; and

FIG. 9 is an enlarged fragmentary side elevational view, taken partly in section of a disconnect switch of the type shown in FIGS. 1 and 2, but showing a modification in the counter-balancing mechanism employed for utilization of the disconnect switch in an inverted position.

Referring to the drawings, and particularly to FIGS. 1 and 2, the structure shown therein comprises a disconnect switch assembly generally indicated by the reference character 10. The switch structure comprises three spaced insulator stacks 11, 12 and 13 which are mounted upon a metal base 14. Each insulator stack comprises a plurality of insulators 15 which are preferably comprised of porcelain or similar material, the number of insulators per stack being optional depending upon the voltage of the system in which the switch is to be utilized. The stacks 11 and 12 are mounted upon fixed pedestals 16, 16 which may be secured to the top of the base 14. The stack 13 is fixedly mounted upon a shaft 17, the end of which is rotatably mounted in a bearing 18 which is secured to the base 14.

A crank 19 is fixably attached to the shaft 17 in any suitable manner at a point below the insulator stack 13 and is adapted for connection to any conventional means for operating the crank to effect rotation of the shaft 17 about its longitudinal axis.

A shaft 20 is fixably attached to and extends upwardly from the top portion of the insulator stack 13 to thus comprise a rigid extension of shaft 17. The upper end of shaft 20 comprises a crank arm 21 which extends generally at an angle substantially horizontal with respect to the base 14 and perpendicular with respect to the axis of rotation of combined shafts 17 and 20.

The outer end of the crank arm 21 is forked at 22, 22,

the fork elements 22, 22 being vertically aligned and apertured to receive a pin 24 upon which is received a ball 25 positioned between the fork elements 22, 22.

As best seen in FIG. 4, an eye bolt 26 is attached for universal movement with respect to the arm 21 by means of an aperture 27 in one end thereof, the aperture having an internal contour slidably mating in socket relationship with the ball 25. The other end of the bolt 26 is slidably received for longitudinal movement within a first bore 28 in one end of a forked link member 29 and a second bore 30 in link extension 31. The bores 28 and 30 are aligned by means of an integral bridging member 32 fixedly spacing the link extension 31 with respect to the link 29 so as to form a cavity 4 having an open side defined by a peripheral lip 5. An adjusting nut 33 is threadedly received on a threaded portion 34 of the bolt 26 located intermediate its ends, and at the same time, the nut 33 is positioned within the cavity 4. The length of the nut along the bolt 26 is less than the breadth of the cavity for permitting predetermined limited longitudinal sliding motion between the bolt 26 and the link 29 which thus cooperate to comprise a slip joint 6 having its limits of movement defined by the vertical sides of the cavity 4. The periphery of the nut 33 is provided with a plurality of teeth 54 extending laterally from the longitudinal axis of the nut and adapted for straddling engagement With. a pin 61 aligned parallel with the bores 28 and 30 and removably secured by any suitable means through suitable apertures in peripheral lip of cavity 4. The pin 61 may be removed to permit adjustment of the nut 33 on bolt 26, whereafter replacement of the pin permits limited rotational movement of the nut with respect to bolt '26 but at the same time permits free movement of the nut 33 across the cavity as the slip joint 6 operates. A cap 64 covers the cavity 4 to protect the slip joint 6'from the elements. The siip joint 6 is so arranged that rotation of the crank arm 21 in response to operation to crank 19 provides for effectively lengthening the link 29 within definitely prescribed limits for substantially separating rotary and swinging movements of the blade 44 in a manner that will be apparent hereinafter. a

The forked link 29, shown in FIGS. 1, 2 and 4 includes a pair of arms 35, 35 at the end opposite the slip joint 6, each of the arms terminating in an aperture 37, 37, respectively, in mating relationship with a pin 39 which passes through the openings 37, 37 and openings 40, 40 in the blade crank 42 which is integral with a tubular blade crank 43. A tubular switch blade 44 is fixed within the crank 43 as by bolts 45, 45 (FIG. 5) and is rotatable therewith when the crank 42 is operated in response to the operation of the link 29 in a manner to be hereinafter described in detail.

The blade 44 is mounted for axial rotation within a pair of spaced aligned bearings 46, 47, said bearing 47 being mounted upon a hinge casting 48, and said bearing 46 being mounted upon a hinge casting extension 49,

' with the extension 49 being fixably attached to and spaced from the casting 48 by means of a pair of substantially parallel integralbridge members 58, 50. The blade crank 42 is carried between the bearings 46 and 47 in abutting relationship therewith so that operation of crank 42 provides free rotation of the blade 44 about its longitudinal axis, but prevents any longitudinal motion of the blade 44 with respect to the hinge casting 48. The hinge casting 48 is rotatably supported by a pair of bearings 51,

52 which are fixed in opposite sides of the hinge casting 48 and extend through the sides of the casting, said bearings 51, 52 being positioned in mating relationship with a pair of threaded openings 53, 54 in a pair of spaced arms 55, 56 on a hinge support member 57. A pair of threaded pivot studs 58, '59 extend through the mating openings 53, 53 and bearings 51, 52 to provide a pivotal relationship between the casting 48 and the bearing support 57. The pivot 58 is comprised of electrically conducting material. Lock nuts 60, 60 are provided on studs 58, 59 for retaining the studs in their properly adjusted position in the threaded openings 53, 53.

The outer end of the tubular blade 44 is flattened as at 62 and to provide suitable contact portions 63, 63 engageable with contacts 65, 65 (FIG. 3) on fixed contact jaws 67, 67.

The fixed contact jaws 67 are of the reverse loop type well known in the art and having the characteristic of, magnetically forcing the blade of a disconnect switch downwardly between the loops in a direction toward the base junction 68 of the loops and against blade stop 73 in response to momentary high currents. The jaws 67, 67 may be composed of zirconium copper, which, when heat treated, combines very high conductivity of about 90% with excellent spring characteristics. The resilient nature of the zirconium copper eliminates the need for additional spring means to bias the jaws 67, 67 toward each other for gripping the switch blade. The contact jaws 67, 67 are fixedly attached to the insulator cap 69 by any suitable means such as bolts (not shown) extending through apertures 70, 70 in the junction 68 of fixed contact jaws 67, 67 A terminal strap 71 is fixedly attached intermediate its end to insulator cap 69 by means of the aforesaid bolts through the aperture 70 in the contact jaws 67, 67. One end 72 of the terminal strap is a connector for connecting the disconnect switch in a circuit. The other end of the strap is a stop 73 extending substantially perpendicular to the body of strap 71 and terminating at a point adjacent the contact "65, 65 on the jaws 67, 67 for engaging the blade 44 in the contact making position as shown in FIG. 1. The insulator cap 69 is an integral part of insulator stack.

A terminal casting 74 is provided to complete connection of the disconnect switch in a circuit, and includes a terminal strap 75 at the outer side wall, a pair of vertically aligned oppositely disposed apertures 76, 76 in the stop and bottom walls of the casting for receiving the previously described shaft 20 which extends vertically therethrough, and a flanged opening 78 on the inner wall for receiving one end of a tubular conductor '79 preferably comprised of copper or other electrical conductor means.

The tubular conductor 79 also serves as a housing for a counter-balancing mechanism generally indicated at 80 and hereinafter described in detail. The other end of the tubular conductor 79 is fixedly attached to a flanged opening in one of the previously described hinge support 57 for connecting the hinge support 57 and other parts of the structure in circuit relationship with the terminal pad 75.

A pair of bearings 81, 81 are fixed in openings 76, 76 in the terminal casting 74 for making engagement with enlarged'portions 83 and 83 of shaft 20, whereby shaft 20 is adapted for freely rotating within the casting 75. A flange 86 is provided on shaft 20 for engagement with one of the bearings 76 to thus effectively support the casting in a fixed vertical position with respect to the hinge support 57, while the rigid conductor 79, being connected at one end to the hinge support 57 and at the other end to the terminal casting 74, prevents the terminal castings- 74 from rotating with the shaft 20.

in order to provide for establishing rotational limits of shaft 29 about its own axis, there is provided a pair of integral limit flanges 87, 88 extending laterally from the shaft 20 intermediate the enlarged portions 83, 83 which flanges are spaced from each other approximately 96 degrees with respect to the axis of rotation of shaft 28 for cooperating with a pair of adjustable stops 89, 99 mounted in and extending through the outer wall. of terminal castings 74 for engaging said flanges to stop the rotation of the shaft 20 at predetermined fixed limit,

assumed that the switch blade is closed with the flat end of the blade horizontally positioned in engagement with the jaws 67, 67 of the fixed contacts and in engagement with the blade stop 73. Under these conditions, the toggle mechanism comprised of link 29, slip joint 6, bolt 26, ball 25, socket 27 and crank arm 21, is in an overtoggle position, as illustrated in FIG. 2 with the limit flange 83 on shaft abutting the limit stop 89, as shown in FIG. 5.

The overtoggle position of the switch when the switch is closed positions the flattened end of the blade in full engagement with the fixed jaws 67, 67. When the arm 21 is rotated counter-clockwise, as viewed from the top in FIG. 2, the toggle mechanism moves through the dead center position to an undertoggle position to effect opening of the disconnect switch.

When the toggle mechanism is in the initial overtoggle position, the nut 33 in slip joint 6 is nearly abutting the end of the link 29, but is spaced slightly from the end of link 29 allowing the blade to rest upon stop 73. As the toggle mechanism moves through the dead center position, the bolt 26 is permitted to slide longitudinally within the bores 28 and 30 to effectively shorten link 29 to permit the toggle mechanism to pass through the dead center position. At the dead center position, the nut 33 abuts the end of link 29 as shown in cross-section in FIG. 4. It is seen that in the overtoggle condition, the space between nut 33 and the end of link 29 introduces a small amount of play in the linkage between the blade 44 and the arm 21. The reverse loop jaws 67, 67 hold the blade 44 in the closed position in response to high fault currents, thus eliminating any necessity for any additional elements in the toggle mechanism to eliminate the play in the linkage.

The further rotation of the arm 21 toward the undertoggle position from the dead center position effects a lengthening of link 29 through the operation of slip joint 6 wherein bolt 26 slides longitudinally in bore 30 on extension 31 and bore 28 on link 29 until the adjusting nut 33 abuts the end of extension 31. It is seen that the lengthening of link 29 through the operation of slip joint 6 eliminates any longitudinal pull on link 29 as arm 21 rotates, but transmits lateral force applied by arm 21 to bolt 26 so that the link 29 provides a lateral force on crank 42 to thus rotate blade 44 in hinge member 48 to etfect disconnection between the blade 44 and contact jaws 67, 67. f Thereafter, continued movement of the arm 21 carries nut 33 into engagement with the inner end of link extension 31 thus preventing further lengthening of the link 29 so that continued movement of arm 21 provides a longitudinal pull on link 29, which force is transmitted through pin 39 and crank 42 to swing blade 44 and hinge 48 upwardly about pivot pin 58, 59 until the blade is in a substantially vertical position whereupon stop 87 on shaft 20 is in engagement with limit stud 90.

To close the disconnect switch, the arm 21 is moved in a clockwise direction, thus swinging the blade between the jaws 67, 67 where it rests upon stop 73. The link 29 contracts at the beginning or end of the swinging movement depending upon the strength of the counterbalancing mechanism hereinafter described. Thereafter, further rotation of the arm 21 efiects movement of the toggle linkage through center and to the overtoggle position whereupon extension of slip joint 6 occurs so that the flat end of the blade 44 is thus rotated into engagement with the fixed contact jaws 67, 67, while the blade itself rests on stop 73.

In order to conduct current from the switch blade 44 through the conductor 79 to the terminal strap 75 without the use of flexible shunts, a bridging member 91 is provided within the casting 48. As shown most clearly in FIG. 5, one arm 92 of the bridging member engages the flat end portion 93 of a conducting plug 94 fixed within the inner end of blade 44 by means of the aforesaid bolts 45, 45, which also fix crank 42 to blade 44. The plug 94 is in direct electrical engagement with the inner periphery of the blade 44. The other arm 95 includes a depression 23 which engages the inner end of pivot stud 58 which is threaded into hinge support 53 and rotatably engaged with hinge casting 48.

The pressure of the arms 92, 95 of the bridge member on the plug 93 and stud 58, respectively, may be adjusted by means of a compression spring 96 which may be compressed against a flange 36 within an aperture portion 38 through the mid portion of the bridge member 91, as shown in FIGS. 5 and 6. A bolt 97 extends through the casting 4S and the aperture 38 in threaded engagement with a nut 98 bearing against the other end of spring 96 and which is prevented from rotating with the bolt by means of an integral guide member 41 extending within the recess 47 adjacent aperture 38 to engage the walls of the recess. In this manner, current is conducted from blade 44 through bridge member 91 to stud 58 and thence through the support 57, conductor tube 79, terminal casting 74 to the terminal strap 75. A cover 77 is provided on the casting to completely protect the bridge member 91 from the elements.

In order to assist the operating crank arm in urging the switch blade from the horizontal closed position to the vertical open position, there is provided the previously mentioned counter-balancing mechanism 80 comprised of a coil spring 99 compressible to oppose the weight Of the blade when in positions other than the vertical. The coil spring 99 is positioned within the previously mentioned conductor tube '79, and extends longitudinally of the tube with one end of said spring abutting the end of tube 79 away from the hinge casting 48 and with the other end abutting a spring guide member 100 positioned across the tube and operable for movement along the length of the tube by means of three rollers 101, 101, 101, only one shown, which rollers are fastened at 120 degrees intervals around the edge of the guide member 100 by any suitable means and are operable to engage the inner periphery of the tube 79 so as to prevent binding between the guide member 100 and the inner wall of tube 79 when the guide member traverses the length of the tube during the operation of the disconnect switch. The force of the spring 99 is transmitted to the hinge casting 48 by means of a link 102 pivotally attached at one end by a suitable pin means 103 to the central portion of the guide member 100 and pivotally attached at the other end to the hinge casting 48 by means of a pin 104 extending through suitable apertures 110 in one end of a pair of spaced flange members 105, 105 extending rearwardly and externally of hinge casting 48 and extending away from the pivot point as established by bearings 51, 52 and pivot pins 58, 59 to thus comprise a lever arm determined by the perpendicular distance from pin 104 to a line connecting pivot pins 58, 59.

It is to be observed that in the counter-balancing mechanism, the force of the spring multiplied by the lever arm as defined by the aforesaid distance between pin 104 and pivots 58, 59 is equal to the gravity force on the blade, bearing and other parts that tend to move the assembly casting counterclockwise about the pivot pin axis defined by pins 58, 59.

In order to provide for counter-balancing, the blade 44 when the disconnect switch is vertically mounted as hereinafter described there is a stop member 106 attached to the walls of hinge support 57 by means of bolts 107, 107, which member is centrally apertured at 108 for passing the link member 102. A central flange 109 is provided around the periphery of the aperture 108 to serve as seat means for the spring 99 in a manner to be hereinafter described.

Referring now to FIG. 8 there is shown the counterbalancing mechanism 80 as previously described, but with the component parts rearranged to provide for counter-balancing the blade 44 when the switch is mounted in 7 the vertical position. Specifically, the coil spring 99 is now arranged for compression between stop member 106 and the guide member 100 in a reversed position so that the spring 99 provides its maximum counter-balancing force when the blade is open and the minimum force when the blade is closed.

In order to provide for counter-balancing, the blade 4-4 when the disconnect is mounted in an inverted position, there is provided an additional pair of apertures 111 in previously described flanges hi5, Hi5 spaced from the first pair of apertures 11%) at a point more remote from the stop member 1% when the switch blade .-4 is closed.

Referring now to FIG. 9, there is shown the counterbalancing mechanism for invertedly mounting the switch. The previously described components of the counter-balancing mechanism are arranged as described for the vertical switch mounting operation as shown in FIG. 8, except that the link 102 is now replaced by a link 112 connected at one end to the previously described pin 103 on the guide member 166 and connected at the other end to the second pair of apertures 1-11 in hinge casting 43. The link 112 includes a curved portion 113 adjacent the end connected to the hinge casting thus allowing the switch blade 44 to fully rotate about pins 53,, 59) torthe fully open condition without binding the switch. As shown in FIG. 9, the spring 99 is compressed to counter-balance the weight of the blade 44 when closed in the inverted position. As the blade drops open to the vertical position, the spring is further compressed, however, the rotation Of the apertures 111 around pivot pins 58, 59 effectively decreases the length of the lever arm between the apertures 111 and pivots 58, 59 with respect to point 103 essentially to zero as the blade 44 reaches the fully open position, thereby providing a diminishing overall counterbalancing force to the blade as it approaches the vertical open position from the horizontal closed position.

From the foregoing description of the counter-balancing means, it is seen that by merely providing a difieren-t link the disconnect switch may be changed from horizontal to vertical mounting. Furthenby providing a difierent link and a different spring design, the disconnect switch may be converted from horizontal to invertedmounting. This adaptability permits the stocking of fewer parts with lower inventory cost and permits rapid assembly of switches to meet the various customer requirements.

Having particularly disclosed preferred embodiments of the invention in accordance with the patent statutes, it should be understood that the invention is not to be limited to this particular embodiment because it will be obvious particularly to persons skilled in the art, that many changes and modifications may be made without departing from the spirit of the invention. Accordingly, it is desired that the invention be interpreted as broadly as possible and that it be limited only as required by the prior art.

We claim as our invention:

1. An electric switch, comprising: a crank arm mounted for rotation on a fixed axis; stationary contact means spaced from said axis; stop means adjacent said contact means; a switch blade rotatable about an axis fixed between said fixed contacts and said crank arm axis; said switch blade axis being perpendicular to the axis of rotation of said crank arm for swinging into engagement with the stop; said blade being mounted for rotary movement about its longitudinal axis to engage said contacts when the blade is in engagement with said stop; an arm fixed on said blade; means connecting said blade arm to said crank arm and including a ball and rocket joint and a slip joint, said slip joint comprising a pair of elements mounted for unopposed relative axial movement in both directions within prescribed limits and pivotally connected respectively to the blade arm and the crank arm for swinging the blade during part of the rotary movement of said crank arm until the free end of the blade is in engagement with the stop and thereafter providing an axial movement of the said elements for rotating the blade during a further portion of the rotary motion of said crank arm to rotate the blade to bring its free end into engagement with said contacts.

2. An electric switch, comprising: a crank arm mounted for rotation on a fixed axis; stationary contact means spaced from said axis; a stop means adjacent said contact means; a switch blade rotatable about an axis fixed between said fixed contacts and said crank arm; said switch blade axis being perpendicular to the axis of rotation of said crank arm for swinging into engagement with the stop; said blade being mounted for rotary movement about its longitudinal axis to engage said contacts'when the blade is in engagement with said stop; an arm fixed on said blade; a link pivotally connected at one end to the distal end ofsaid arm only for movement toward and away from said arm; a bore in said link spaced from said link pivot and extending substantially parallel to the longitudinal axis of the blade and perpendicular to the axis of the operating crank; a cavity in said link having an opening in the side of said link and extending transversely through said bore; a bolt slidably received in said bore for axial movement therein, a threaded portion on said bolt intermediate its ends, a nut in said cavity and threadedly received on said threaded portion of said bolt, said nut having a length lessthan the length of the cavity longitudinally of the bore to permit the bolt to slide freely within the bore within the limitations established by the ends of the cavity; said nut having a toothed periphery; and means removably attached to said link adjacent the Opening to said cavity and engageable with any pair of said teeth for preventing rotation of the nut with respect to the link. V

3. An electric switch, comprising: a crank arm mounted for rotation on a fixed axis; stationary contact means spaced from said axis; a stop means adjacent said contact means; a switch blade rotatable about an axis fixed between said fixed contacts and said crank arm; said switch blade axis being perpendicular to the axis of rotation of said crank 'for swinging into engagement with the stop; said blade being mounted for rotary movement about its longitudinal axis to engage said contacts when the blade is in engagement .with said stop; an arm fixed on said blade; a link pivotally connected at one end to the free end of said arm only for movement toward and away from said arm; a bore in said link spaced from said link pivot and extending substantially parallel to the longitudinal axis of the blade and perpendicular to the axis of the operating crank; a cavity in said link having an opening in the side of the link and extending transversely through an intermediate portion of the bore, a bolt slidably received in said bore for axial and rotational movement therein, a threaded portion intermediate the ends of said bolt, a nut in said cavity and threadedly received on said threaded portion of said bolt, said nut having a length less than the length of the cavity longitudinally of the bore to permit the bolt to slide freely within the bore within the limits established by the movement of the nut within the cavity; said nut having a toothed periphery; lip means on opposite ends of said cavity in parallel alignment with said bore; pin means extending through said lip means and removably attached thereto; the periphery on said nut comprised of teeth, any pair of which straddles said pin when the pin is in the apertures, whereby the nut is prevented from rotating with respect to the link but may freely move longitudinally with respect thereto.

4. An electric switch, comprising: a crank arm mounted for rotation about a fixed axis; stationary contact means spaced from said axis; a stop means adjacent said contact means; a switch blade rotatable about an axis fixed between said fixed contacts and said crank arm; said switch blade axis being perpendicular to the axis of rotation of said crank arm for swinging into engagement with the stop; said blade being mounted for rotary movement about its longitudinal axis to engage said contacts when the blade is in engagement with said stop; an arm fixed on said blade; means connecting said arm on said blade to said first mentioned crank arm and including a ball and socket joint and a slip joint, said slip joint comprising a pair of elements mounted for unopposed relative axial movement in both directions within prescribed limits and pivotally connected respectively to the blade arm and the crank arm for swinging the blade during part of the rotary movement of said crank arm until the free end is in engagement with the stop and thereafter providing a relatively axial movement of the elements for rotating the blade during a further portion of the rotary movement of the crank arm to rotate the blade to bring its free end into engagement with said contacts; and said fixed contacts being comprised of a pair of oppose reversed loop contact members operable to grip the free end of the blade when the blade is in the fully closed condition and to magnetically hold the blade against said stop in response to overcurrent conditions.

5. An electric switch, comprising: a crank arm mounted for rotation about a med axis; stationary contact means spaced from said axis; a stop means adjacent said contact means; a switch blade rotatable about an axis fixed between said fixed contacts and said crank arm; said switch blade axis being perpendicular to the axis of rotation of said crank arm for swinging into engagement with the stop; said blade being mounted for rotary movement about its longitudinal axis to engage said contacts when the blade is in engagement with said stop; an arm fixed on said blade; means connecting said arm on said blade to said first mentioned crank arm and including a ball and socket joint and a slip joint, sa d slip joint comprising a pair of elements mounted for unopposed relative axial movement in both directions within prescribed limits and pivotally connected res ectively to the arm and the crank arm for swinging the blade during part of the rotary movement of said crank until the free end is in engagement with the stop and thereafter providing a relatively axial movement of the elements for rotating the blade during a fort ier portion of the rotary movement of the crank arm to rotate the blade to bring its free end into engagement with said contacts; said fixed contacts being comprised of a pair of opposed reversed loop contact members operable to grip the free end of the blade when the blade is in the fully closed condition and to magnetically hold the blade against said stop in response to overcurrent conditions, and said fixed contacts comprising a pair of reversed loop members serving as the sole means for holding the blade against the stop in response to o ercurrent conditions.

6. An electric switch, comprising: fixed contact means; a switch blade adapted for swinging motion about a fixed pivot means spaced from said contact means to engage the free end with said fixed contacts; said fixed pivot means comprised of electrical conducting material; electrical conducting means connecting the switch blade to the pivot means; a blade operating mechanism connected to the blade and including a crank rotatable about a fixed pivot spaced from said first pivot means; a terminal support mounted for rotation upon said crank; a tubular conductor rigidly connecting said first pivot means in electrical conducting relationship to said terminal support;

counter-balancing means for opposing the weight of the blade in the various positions around the fixed pivot means; said counter-balancing means comprising spring means mounted internally of said tubular conductor and having one end of said spring means abutting one end of said tubular conductor, link means connecting the other end of the spring and extending outwardly of the tubular conductor through the other end thereof and connected in pivotal relationship with the switch blade mechanism.

7. An electric switch, comprising: fixed contact means; a switch blade adapted for swinging motion about a fixed pivot means spaced from said contact means and operable to engage the free end with said fixed contacts; said fixed pivot means comprised of electrical conducting material; electrical conducting means connecting the switch blade to the pivot means; a blade operating mechanism connected to the blade and including acrank rotatable about a fixed pivot spaced from said first pivot means; a terminal support mounted for rotation upon said crank and comprised of electrical conducting material; a tubular conductor rigidly connecting said first pivot means in electrical conducting relationship to said terminal support; counter-balancing means for opposing the weight of the blade in the various positions around the fixed pivot means; said counter-balancing means comprising spring means mounted internally of said tubular conductor and having one end thereof in abutting relationship with the one end of said tubular conductor; link means connected to the other end of the spring and including spring guide means abutting the other end of the spring and including roller means engaging the internal walls of the tubular conductor; said link means extending outwardly through the outer end of the tubular condoctor in pivotal connection with the switch blade mechanism.

8. An electric switch, comprising: fixed contact means; a switch blade mounted for movement about a fixed pivot means spaced from said contact means to engage said fixed contacts; terminal means spaced from said pivot means on the side of said pivot means away from said fixed contacts; housing means connecting said terminal means and pivot means; crank operating means for moving said blade into engagement wtih said fixed contact means; spaced lever arm means on said blade; counterbalancing means for said blade; said counter-balancing means including a spring within said housing and adapted to abut one end of said housing when the switch is horizontally mounted and adapted to abut the other end of the housing when the switch is vertically mounted or is invertedly mounted; interchangeable link means connecting the other end of said spring to one or the other of said two spaced lever arms depending upon whether the switch is mounted horizontally, vertically, or invertedly to counter-balance the blade throughout its swinging movement about the fixed pivot means.

Refe ences titted in the file of this patent UNITED STATES PATENTS 2,531,165 Scheuermeyer Nov. 21, 1950 2,835,770 Foti May 20, 1958 2,963,560 Koerner et al. Dec. 6, 1960 

1. AN ELECTRIC SWITCH, COMPRISING: A CRANK ARM MOUNTED FOR ROTATION ON A FIXED AXIS; STATIONARY CONTACT MEANS SPACED FROM SAID AXIS; STOP MEANS ADJACENT SAID CONTACT MEANS; A SWITCH BLADE ROTATABLE ABOUT AN AXIS FIXED BETWEEN SAID FIXED CONTACTS AND SAID CRANK ARM AXIS; SAID SWITCH BLADE AXIS BEING PERPENDICULAR TO THE AXIS OF ROTATION OF SAID CRANK ARM FOR SWINGING INTO ENGAGEMENT WITH THE STOP: SAID BLADE BEING MOUNTED FOR ROTARY MOVEMENT ABOUT ITS LONGITUDINAL AXIS TO ENGAGE SAID CONTACTS WHEN THE BLADE IS IN ENGAGEMENT WITH SAID STOP; AN ARM FIXED ON SAID BLADE; MEANS CONNECTING SAID BLADE ARM TO SAID CRANK ARM AND INCLUDING A BALL AND ROCKET JOINT AND 